The goal of the application is to obtain a high-capacity computer server than can support the diverse data management and analytical needs of our NIH-funded health care and aging research. The NBER has acquired an enormous volume of health care data, and is engaged in a comprehensive research effort to analyze issues related to health care utilization patterns and health care costs. Two sets of data in particular have strained our current computer capacity. The first contains complete medical claims records for well over 20 million Medicare beneficiaries between 1984 and 1992, including all Medicare beneficiaries who were treated at any time during this period for heart disease, cancer, cerebrovascular disease, or cataracts. The second contains complete medical claims records for over 3 million employees and dependents covered by employer-provided health insurance plans between 1990 and 1992. Both data sources will be updated through 1995 later this year. A series of NIH grants have been awarded to analyze these data, and the proposed computer server would enable these projects to be conducted more efficiently than is currently feasible. The specific aims are: (1) to enable efficient data management and multi-user access to the NBER~s large medical claims data files, supporting the activities of three full-time data management professionals, and the analytical needs associated with six NIH- funded research projects using medical claims data, (2) to provide the computational capacity and disk space to handle computationally demanding analyses of our largest data files; and to accelerate the processing time required for all computing tasks using our large Medicare claims and employer health insurance claims data files, (3) to provide efficient on-line access to our health care and aging- related data, eliminating the time-consuming process of repeatedly reading and extracting information from multiple tapes, particularly for data components that are used frequently, or by multiple investigators. The computer server proposed in this application would accelerate a whole range of NIH-funded research projects.